Biomedical subjects
Publications and source records attributed to R Felix.
The dimeglumine salt of the Gd-DTPA complex has a strong paramagnetic effect and a very low toxicity in animals. This report of its use in human volunteers confirms its low toxicity and indicates its usefulness in the enhancement of signal intensity of the kidney and bladder.
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The effect of a beta-receptor blockade on the mucociliary clearance was studied in 24 patients without pulmonary disease but with coronary heart disease. No deterioration of mucociliary clearance was recorded under medication with 2 X 50 mg metoprolol or 2 X 2.5 mg mepindolol per day. In contrast, mucociliary clearance deteriorated significantly under medication with 2 X 40 mg propranolol.
Rat calvaria cells previously cultured for 7 days in the presence of 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) or dichloromethylenebisphosphonate (Cl2MBP), showed a decrease in the glycolytic pathway. When glycolysis was analyzed under anaerobic conditions, this effect was not observed. The inhibition by the bisphosphonates occurred to a similar degree regardless of whether lactate production was measured in whole cells or in cell homogenates. Bisphosphonates added directly to the homogenate had no inhibitory effect. Thus, the effect is not a direct one and is unlikely to be due to a soluble mediator in the cytoplasm.
We studied 46 patients with a history of transmural myocardial infarction or angiographic evidence of coronary artery stenosis with both conventional contrast ventriculography and digital subtraction ventriculography from May to September 1982. Urografin 76, 30 ml, was administered at a flow rate of 18 ml/s, by means of a catheter in the superior vena cava during digital subtraction ventriculography (DSV). Results of the latter were compared with conventional contrast ventriculograms. The correlation coefficient was r =0.938 (p less than 0.001) for determination of ejection fraction with both methods. The data in individual cases suggest that DSV is more sensitive than conventional contrast ventriculography in determination of severely reduced ejection fractions. The methods are practically identical in qualitative evaluation of disorders of regional wall motion in the anterolateral region, while DSV is more sensitive than conventional ventriculography in evaluating the apical region. Sensitivity was 85.7% when the two methods were compared in evaluation of the inferior region of the left ventricle. Both methods are identical in demonstration of severely deformed ventricles. Digital subtraction ventriculography may replace conventional contrast ventriculography in some of the situations discussed above.
A variety of bisphosphonates with aliphatic side chains of increasing length, as well as 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (AHPrBP, formerly APD), dichloromethylene-bisphosphonate (Cl2MBP, formerly Cl2MDP), and dibromomethylene bisphosphonate (Br2MBP, formerly Br2MDP), were compared in vitro and in vivo to find (a) a possible relationship between structure and activity in order to give some indication about their mechanism(s) of action on bone and (b) the most efficient and safe compound having an effect on bone resorption. Some relationship was found between inhibition of calcium phosphate precipitation in vitro and of mineralization in vivo. No correlation existed, however, between any parameter measured and bone resorption. The number of calvaria cells in culture was decreased by compounds with a chain length greater than 5-C, by AHPrBP, Cl2MBP, and Br2MBP. Lactate production by these cells in vitro was increased by the long chain bisphosphonates and AHPrBP, and was decreased by Cl2MBP. No good correlation existed between the inhibition of bone resorption measured in vitro on calvaria and that seen in vivo on rat tibiae metaphyses. The latter was inhibited the most efficiently by the bisphosphonates longer than 5-C and by AHPrBP; these were 10 times more effective than Cl2MBP. Taking into account all factors, 1-hydroxypentylidene-1,1-bisphosphonate and AHPrBP seem to be the most active compounds to inhibit bone resorption.
A large-pore gel for electrophoresis in the presence of sodium dodecyl sulfate, composed of 2.55% polyacrylamide crosslinked with 2.75% methylenebisacrylamide, is described. This gel has a resolving power for very high molecular weight proteins and can be stained with silver. The gel is suitable for fractionation of factor VIII/von Willebrand factor directly from plasma samples. Visualization by silver staining revealed a series of covalently bound multimers with molecular weights of up to 8 X 10(6). The procedure described should be useful also for studies on other very high molecular weight proteins and nucleic acids.
Following venous injection of radiopaque contrast material, digital subtraction angiography was employed to examine coronary bypass grafts in ten patients. In LAO projection 18 of 24 grafts could be identified. This result shows the ability to assess patency of bypass grafts using computerized fluoroscopy.
Nineteen patients suspected of having intracavitary masses were examined by echo-cardiography and computer tomography. One 1 cm. thrombus on the mitral valve could be demonstrated only on the echo-cardiogram and was interpreted as a tumour. Both CT and echo-cardiograms produced occasional false negative findings with cardiac thrombi, which were ultimately diagnosed by the other method or by ventriculography. Differentiation between a thrombus and a tumour depends essentially on its localisation and on the history, and some morphological criteria. Echo-cardiography and densitometric measurements did not assist in the differential diagnosis. CT may be able to differentiate thrombus from tumour if the latter contained fat or has become cystic.
The degree of alveolar deposition of inhaled microparticles, which is affected by airway patency, was studied in 16 asymptomatic smokers with small airways disease. Compared to healthy subjects (n = 12) as well as to patients with chronic obstructive lung disease (COLD, n = 14) significant differences in mean alveolar particle deposition were encountered. The results indicate that in both patient groups the lower-lung regions were most affected by airway obstruction. In patients with peripheral airways disease there was no difference in the degree of right- and left-lung aerosol deposition whereas in patients with COLD obstructive airway alteration was found to affect preferably the right lung region.
Intravenous digital subtraction angiography has been employed to examine arteries in 600 patients. Conventional angiography was used in 41 cases where insufficient DSA was made, or as definitive preoperative investigation. In 88% the digital subtraction angiogram is diagnostic, and conventional angiography then shows little more additional information.
Intravenous digital subtraction angiography (DSA) was obtained in 55 cases after reconstructive procedures of the carotid arteries, the pelvic and lower limb arteries. In 48 cases (87%) the studies were of technically satisfactory or good quality. On DSA 32 vascular reconstructions were normal and 16 had typical complications like occlusions, stenoses, aneurysms and insufficient run-off. -Experience indicates that the spatial resolution of DSA is adequate for clinical purposes such as determining graft patency or the presence of postoperative complications. Because DSA is less invasive than catheter angiography, postoperative evaluation of patients having undergone peripheral surgical revascularization should start with DSA.
After in-vivo labeling of red blood cells with 99mTcO4, the radioactivity of different parts of the body is proportional to the regional blood volume. This technique allows the simultaneous registration of drug-induced changes of the local blood volume. We examined the influence of nitroglycerin on the blood volume distribution in patients with coronary artery disease (n = 10) and chronic heart failure (n = 8). Compared with the controls (n = 8) we observed in the nitroglycerin-groups a significant decrease of blood volume over the heart and the liver, whereas there was an increase of the blood volume over the extremities. It is pointed out that functional whole-body scanning is a useful radiological technique for the non-invasive study of pharmacologically caused changes of the local blood volume in man.
Tomographic studies and time-dependent tomograms on phantoms and patients were carried out using a 7-pinhole collimator in order to study the clinical value of ECG-triggered tomographic radionuclid ventriculography. A suitable computer programme has been developed. The results have shown that it is possible to evaluate local contraction abnormalities by this method. Using a left oblique position of the collimator (LAO [45 degrees]-cranial [15 degrees] ), emission computer tomography is aligned with the longitudinal axis of the heart. In this way, a single projection is sufficient to show the motility of the anterior and posterior walls and of the septum. Hypokinesis, akinesis or dyskinesis can be recognised visually. The localisation and extent of the defect can be determined through the 7-pinhole collimator. Reconstructed images of the triggered radionuclid scintigrams show excellent marginal definition. In the RAO projection, the left ventricle can be seen without superimposition and images obtained which equal those of a first-pass technique.
Quantitative radioaerosol lung imaging was performed in 30 asymptomatic smokers selected on the basis of abnormal findings in pulmonary function tests of small airways. Regional clearance rates of inhaled 99mTc-labelled human serum albumin minimicrospheres (HAMM) were determined over upper, middle, lower, central, and peripheral anterior lung zones. In contrast with the findings in 20 nonsmokers without evidence of small airways dysfunction significant mucociliary clearance delay occurred in the peripheral and upper pulmonary regions. An aerosol distribution index (ADI) measures the homogeneity of distribution of inhaled particles in the lung. A significant difference in the mean values of ADI was found, indicating an abnormal uneven radioaerosol distribution pattern in the smokers with small airways disease.
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The validity of two-dimensional echocardiography (2-D echo) and computed tomography (CT) in the detection of intra- and paracardial tumors and thrombi was compared in 32 patients: 7 endocardial myxomas, 1 left ventricular fibroma, 2 paracardial cysts, 1 paracardial tumor, and 21 thrombi. In 16 cases intraoperative findings served as a control. The 2-D echo is easier to handle and free of radiation of contrast media. CT can visualize cardiac tumors independently of their location, whereas 2-D echo sometimes insufficiently images paracardial and right ventricular structures. It must be considered an advantage that 2-D echo detects mobile tumors such as those attached to valves, which the CT will not show. The tissue involved is more likely to be characterized by CT, although results are unreliable. However, in all cases tumors could be differentiated from thrombi by means of additional diagnostic criteria, such as the pattern of wall motion or valve motion. 2-D echo and CT therefore appear to be complementary methods rather than competitive ones. Invasive diagnostic procedures are required only to answer particular questions, e.g., concerning the coronary arteries.